Feat: update ansible-lint to version 4.0.0

Signed-off-by: Hadrien Patte <hadrien.patte@protonmail.com>

.gitlab-ci.yml

@@ -1,14 +1,18 @@
 ---
-image: quay.io/ansible/molecule:2.19
+image: python:3.6
 
 stages:
   - lint
 
 yamllint:
   stage: lint
-  script: yamllint -c .yamllint.yml .
+  script:
+    - pip install yamllint==1.15.0
+    - yamllint -c .yamllint.yml .
 
 ansible-lint:
   stage: lint
-  script: ansible-lint *.yml
+  script:
+    - pip install ansible-lint==4.0.0
+    - ansible-lint *.yml
 ...